We seek to examine the composition and potential mutagenicity, carcinogenicity, and atherogenicity of the very polar, highly oxidized sterol derivatives formed from cholesterol during the ordinary course of air oxidation. Whereas the common autoxidation products of cholesterol have been subjected to much investigation which now suggests possible toxic properties for some, no chemical or biological investigation has ever been reported of the very polar sterols known to be formed along with the common autoxidation products. The present research proposal will submit this very polar fraction to definitive chemical examination, with all major sterol components being isolated, purified, characterized, and structures elucidated. The identified sterol derivatives will be evaluated for their mutagenicity by means of the bacterial mutagen testing procedures using mutant Salmonella typhimurium. Other testing will not be a specific part of this proposal, but the sterols recovered will be made available to other testing programs which may evaluate the important biological properties (carcinogenicity, atherogenicity).